Automatic driving device for machine tools



June26, 1951 E. lFANGl-:R 2,558,252

AUTOMATIC DRIVING DEVICE FCR MACHINE Toons Filed Aug. 3, 1946 /NVEA/ron.- EDUA no /FANGER Patented .une 26, 1951 AUTOMATIC DRIVING DEVICE FOR MACHINE TOOLS Eduard Ifanger, Uster, Switzerland, assignor to Edouard Dubied & Cie., S. A., Neuchatel, Switzerland Application August 3, 1946, Serial No. 688,275 In Switzerland August 28, 1945 4 Claims. (Cl. 279-33) The present invention relates to an automatic chuck for machine tools, especially lathes, having atleast two gripping dogs mounted on the headstock and gripping the piece of work by the action of centrifugal force.

Y -In the chuck according to the invention, the dogsj'are provided with adjustment members bearing against an'axially movable, conical member which can. be moved manually against the action of a spring for disengagement of the dogs from the work. When the conical member is returned to its rest position the dogs or gripping .jaws are free to be independently pressed against the work by centrifugal force and the reaction of the `turning operation.

One embodiment of the invention and a modication thereof are illustrated in the drawings,

vin which Fig. 1 shows a chucking device according to the invention in a longitudinal section;

Fig. 2 kis a front view of the device shown in Fig. 1;. Fig. 3 is a cross section through the device taken along line -IIl--III in Fig. 1; Fig. 4 is a longitudinal section through a modified chuck according to the invention, and Fig. 5 is a front view of the chuck shown in Eig. 4. -In the drawings, the chuck is shown as used in. a lathe, only those parts of the headstock being illustrated which are absolutely necessary for the understanding of the invention, other parts b ngomitted. A case I is mounted on the front d of the hollow spindle 2 of the lathe. A ifi'ember 4 is screwed in the sleeve 3 lining the bore of the spindle. The pointed live center 5 of thel lathe is guided in an extension 4' of member,4.which extension extends through the interior ofthe headstock and simultaneously serves as a guide for a concentric cone 6. A transverse pin 25 is situatedin a transversal slot in member -4 Vat the forward end of a central rod 8 which is 'longitudinally movable in member 4, the

latter having two longitudinal diametrically disposed slots accommodating two axially movable keys 24, the outer ends of which bear against the base of cone 6. A disengagement mechanism 1 of conventional design is situated at the rear end of the spindle and comprises a transverse member 26, by means of which rod 8 can be moved in axial direction. Case I is closed at the front by a lid I0. Between this lid and cone 6 a helical spring 9 is inserted which surrounds the extension 4' and tends to press cone 6 and rod 8 backwards, i. e. to keep it in the illustrated initial or rest position. Two pins I 2 are arranged diametrically opposite to each other in the lid I0, the gripping jaws II being attached to the outward ends of pins I2. These jaws have, opposite each other, eccentrically curved and toothed clamping surfaces I3 for gripping the work I4. Due to the eccentric shape of the gripping surfaces I3 pieces of work of various diameters can securely be clamped between them. Swinging arms I 6, provided with counterweights I5 are fixed on the pins I2 inside the case I. Adjusting screws I'I, which with their inner pointed ends are positioned diametrically opposite to each other and bear against the circumference of cone 6, are screwed in the ends of arms I6` Flat springs I8, attached to the arms I6, bear against the inner wall of case I and press the arms I6 towards the axis of rotation of the chuck and hold the gripping jaws or dogs II in closed position. By moving rod 8 to the right, as seen in Fig. 1, cone 6 is pressed in the same direction. and this causes a swinging of the arms I6 into a position in which the gripping jaws are open. The gripping range of the jaws can -be altered by adjusting the screws I'l. The mode of operation of the device described is as follows:

In order to grip a piece of Work the disengagement device I is manipulated and cone 6 is moved forward by means of the rod 8 and the keys 24 against the action of spring 9. The arms I6 are thus moved outwards and the gripping jaws I I opened. Thereupon the work I4 is placed on the live center 5 and the disengagement device 'I allowed to return to its initial position. Consequently, cone 6 is returned to its initial position by the action of spring 9, and the arms I6 are swung inwards by the flat springs I8. until the toothed clamping surfaces I3 of the gripping jaws II engage the piece of work I4 and grip it. Clamping and securely holding the work between the gripping jaws I I is eifected by the centrifugal action of the counterweights I5 and by the reaction of the resistance of the work I4 to the turning operation, whereby the teeth of the clamping surfaces I3 bite into the work. By adjustment of screws I'l, which can be reached by a screw driver through holes I9 in case I (Fig. 3), the distance between the clamping surfaces can be adapted to the diameter of the work to be machined so that the distance between the clamping surfaces when in open position is about 2 mm. greater than the diameter of the work and the latter can be easily inserted between,

the gripping jaws Il.

Instead of the external cone 6, just described,

a guide iing with internal conical surfaces may be used as illustrated in Figs. 4 and 5. 'I'he design of spindle 2 with member 4 and extension 4 and of case is substantially the same as that described above. Two pins |2', diametrically opposite to each other, are screwed in the lid l' of the ease, and the gripping jaws which serve at the same time as centrifugal weights and are provided with toothed clamping surfaces I3 in the same manner as described above, are supported on the outer ends of the pins |2'. A guide ring 20 having two 'frustoconical cavities 2| can be moved forward by the longitudinal keys 24 against the action of spring 9 and is arranged concentrically around the extension 4. Pins 22 which are situated parallel Ato the rotation axis and on a diameter of the device extend into the frustoconical cavities 2| through slots 23 in the lid of case I and are screwed as adjustment members into the gripping jaws Pins 22 are engaged by the inner conical surfaces of cavities 2| in ring 20 when the latter is moved to the right and cause disengagement of dogs |I from the work. By screwing the pins 22 inwards or outwards, an adjustment of the distance between the eccentric surfaces of the dogs can be achieved similar to that in the rst embodiment.

Since in both embodiments the gripping clamping surfaces I3 are not rigidly coupled with each other by an adjustment ring but `move wholly independently of each other towards the piece of work to be gripped, a secure support of both gripping jaws against centred as well as against eccentric pieces of work is guaranteed.

In the embodiment according to Figs. 4 and 5 eccentric heads may also be provided at the inner end of the adjustment pins 22 and the pins rotatably arranged in the jaws in order to perform an adjustment of the movements of the gripping jaws.

In lathes with a spindle without a bore the described device may, in a similar manner, be arranged at the end of the spindle. More than two gripping jaws may of course be provided.

I do not limit my invention tb the structure shown and described as modifications, within the scope of the appended claims, may be made without departing from the spirit of my invention. Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. An automatic chuck for machine tools, particularly lathes, comprising, in combination, a head member; work engaging means individually pivoted on said head member; and disengaging means comprising resilient means and a control member having a conical surface portion and being movable against the action of said resilient means substantially transversely to the movement of said work engaging means for disengaging the latter from the work; each of said work engaging means comprising means abutted by said conical surface portion upon movement thereof, said last mentioned means being adjustable and affording individual adjustment of the position of said work engaging means relative to the head member.

2. An automatic chuck for machine tools, particularly lathes, comprising, in combination a head member; work engaging means individually pivoted on said head member; and disengaging means comprising resilient means and a control member having a conical surface portion and being movable against the action of said resilient means substantially transversely to the movement of said work engaging means for disengaging the latter from the work; each of said work engaging means comprising a pivot portion, a dog at one end of said pivot portion, an arm at the other end of said pivot portion and having a free end portion, and an adjustment screw screwed into said free end portion and having an end adapted to be abutted by said conical surface portions.

3. A chuck as defined in claim 2, comprising resilient means interposed between said head member and the distal side of said arm with respect to said end of said screw.

4. An automatic chuck for machine tools, particularly lathes, comprising, in combination, a head member; work engaging means individually pivoted on said head member; and disengaging means comprising resilient means and a control member having conical surface portions and being movable against the action of said resilient means substantially transversely to the movement of said work engaging means for disengaging the latter from the Work; each of said work engaging means comprising a pivot portion and a dog extending from one end thereof and transversely to its rotation axis, and a member adjustably connected with said dog and having an end portion adapted to be abutted by one of said conical surface portions.

EDUARD IFANGER.

REFERENCES CITED The following-references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 141,593 Root Aug. 5, 1873 1,149,148 Miller Aug. 3, 1915 FOREIGN PATENTS Number Country Date 511,975 Great Britain Aug. 28, 1939 526,948 France of 1921 

